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\(\dfrac{x}{27}=\dfrac{2}{9}-\dfrac{1}{3}\Rightarrow\dfrac{x}{27}=-\dfrac{1}{9}\Rightarrow\dfrac{x}{27}=\dfrac{-3}{27}\Rightarrow x=27\)
\(\dfrac{x}{27}=\dfrac{2}{9}-\dfrac{1}{3}=-\dfrac{1}{9}\Rightarrow x=-\dfrac{1}{9}.27=-3\).
\(a.2^{x+2}-2^x=96\\ 2^x\cdot4-2^x=96\\ 2^x\cdot\left(4-1\right)=96\\ 2^x\cdot3=96\\ 2^x=96:3\\ 2^x=32\\ 2^x=2^5\\ =>x=5\)
\(2^{x+1}\cdot3^y=12^x\\ 2^{x+1}\cdot3^y=3^x\cdot2^{2x}\\ \left\{{}\begin{matrix}2^{x+1}=2^{2x}\\3^y=3^x\end{matrix}\right.\\ \left\{{}\begin{matrix}x+1=2x\\y=x\end{matrix}\right.\\ \left\{{}\begin{matrix}x=1\\y=x=1\end{matrix}\right.\\ \left\{{}\begin{matrix}x=1\\y=1\end{matrix}\right.\)
\(c.10^x:5^y=20^y\\ 10^x:5^y=5^y\cdot4^y\\ 10^x=10^{2y}\\ =>x=2y\)
a) \(A=\left(\dfrac{\sqrt{x}}{\sqrt{x}-1}-\dfrac{1}{x-\sqrt{x}}\right):\left(\dfrac{1}{\sqrt{x}+1}+\dfrac{2}{x-1}\right)\)
\(=\left(\dfrac{\sqrt{x}}{\sqrt{x}-1}-\dfrac{1}{\sqrt{x}\left(\sqrt{x}-1\right)}\right):\left(\dfrac{1}{\sqrt{x}+1}+\dfrac{2}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\right)\)
\(=\dfrac{x-1}{\sqrt{x}\left(\sqrt{x}-1\right)}:\dfrac{\sqrt{x}-1+2}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}{\sqrt{x}\left(\sqrt{x}-1\right)}:\dfrac{\sqrt{x}+1}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{\sqrt{x}+1}{\sqrt{x}}:\dfrac{1}{\sqrt{x}-1}=\dfrac{\sqrt{x}+1}{\sqrt{x}}.\left(\sqrt{x}-1\right)=\dfrac{x-1}{\sqrt{x}}\)
b) \(A=2\Rightarrow\dfrac{x-1}{\sqrt{x}}=2\Rightarrow x-1=2\sqrt{x}\Rightarrow x-2\sqrt{x}-1=0\)
\(\Rightarrow x-2\sqrt{x}+1=2\Rightarrow\left(\sqrt{x}-1\right)^2=2\Rightarrow\left[{}\begin{matrix}\sqrt{x}-1=\sqrt{2}\\\sqrt{x}-1=-\sqrt{2}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}\sqrt{x}=\sqrt{2}+1\\\sqrt{x}=1-\sqrt{2}\left(l\right)\end{matrix}\right.\Rightarrow x=\left(\sqrt{2}+1\right)^2=3+2\sqrt{2}\)
c) \(A< 0\Rightarrow\dfrac{x-1}{\sqrt{x}}< 0\) mà \(\sqrt{x}>0\Rightarrow x-1< 0\Rightarrow x< 1\Rightarrow0< x< 1\)
1 will go
2 are going to do
3 has studied
4 has been
5 Did they put
6 has worked
7 will go camping
9 haven't met
10 are going to have - will have
11 received
12 won't plau
13 has lived
14 will come
15 has just decided
16 have ever seen
17 have meet
18 visited
19 playing
20 to ride
`Answer:`